The present invention generally relates to an automatic vending system and more particularly, to a control arrangement for an automatic vending machine, which determines whether or not an article or commodity can be vended by an amount or sum of coins inserted by a customer.
In the case where the sum or amount of coins inserted by the customer is equal to the selling price for the commodity, it is clear that such a commodity is vendible, but if the sum of the inserted coins exceeds the selling price, it is necessary to determine the vendibility of said commodity by detecting whether or not a difference therebetween can be paid out as change. Coins which may be paid out as change include two sorts of coins, i.e., those preliminarily stored in a change coin stocking section and those inserted by the customer at that time for purchasing, and thus, a decision must be made for judging whether or not a difference between the sum of the inserted coins and the selling price of the commodity can be paid out as change, by finding the difference based on the combination of the two sorts of coins as referred to above.
Conventionally, there has been disclosed, for example, in U.S. Pat. No. 4,056,181, an automatic vending machine of the above described type. In the above prior art, it is so arranged that the number of coins inserted by a customer is calculated according to the kinds thereof, while the coin detectors for detecting presence or absence of change in the change coin reservoirs are provided so as to judge whether or not the difference between the sum of inserted coins and the selling price may be paid out as the change, based on the number of inserted coins and the detecting outputs of the coin detectors. The above known system includes a subtractor for sequentially subtracting the smallest unit value from the sum of coins inserted by the customer, so that in the case where the remaining sum after the subtraction can be paid out by the coins accommodated in the change coin reservoir, or where no change is present in the change coin reservoir and the remaining sum can be paid out within the number of inserted coins, it is so judged that vending is possible with respect to the selling price which requires the remaining sum to be paid out as change during the vending. In this prior art, however, owing to the arrangement that the smallest unit value is sequentially subtracted from the sum of inserted coins, the vendibility is to be judged with respect to all prices within the sum of the inserted coins. Accordingly, since the vendibility is determined with respect to prices not included in the selling price, the processing time for the judgment is undesirably prolonged. Moreover, the processing itself for subtracting each of the smallest unit values from the sum of inserted coins, has the disadvantage that the processing time becomes long as the sum of the inserted coins increases.